JP2002221819A - Toner and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner which suppresses fluctuation in the electrification characteristics of the toner repeatedly used, which suppresses as much as possible melt-sticking of the toner or filming on a latent image carrying body due to free external additives, and which can form stable images for a long time. SOLUTION: The toner is prepared by externally adding a fine powder material containing Mg to color particles containing at least a binder resin and a coloring agent. The isolation rate of the Mg atoms to carbon atoms is >=0.001% and <=10%. The BET specific surface area of the toner is >=0.5 m2/g and <=30 m2/g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a toner used in a recording method utilizing an electrophotographic method, an electrostatic recording method, a magnetic recording method, or the like, a toner used in a full-color image forming method, or a toner jet method. The present invention relates to a toner used in an image forming method. More specifically, the present invention relates to electrophotography such as a copying machine, a printer, and a facsimile, forming a toner image on an electrostatic latent image carrier in advance, and then transferring the image onto a transfer material to form an image. The present invention relates to a toner used for electroprinting and an image forming method, or a toner that directly discharges toner onto a recording material by a toner jet method to obtain an image.

[0002]

2. Description of the Related Art Conventionally, electrophotography has been disclosed in U.S. Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910.
(U.S. Pat. No. 3,666,363) and Japanese Patent Publication No. 43-24748 (U.S. Pat.
No. 1,361). Generally, a photoconductive substance is used to form an electric latent image on an image carrier (photoreceptor) by various means, and then the latent image is developed with toner, and if necessary, directly or directly. After the toner image is transferred to a recording material such as paper by using indirect means, it is fixed by heating, pressure, heating and pressurizing, or solvent vapor to obtain a copy. The toner remaining on the photoreceptor without being transferred onto the recording material is cleaned by various methods to repeatedly obtain a copy image.

As a method for visualizing an electric latent image, a cascade developing method, a magnetic brush developing method, a pressure developing method and the like are known.

On the other hand, in the electrophotographic industry, the resolution of an image of a printer device or the like has been increased to 1200 or 2400 dpi. Accordingly, a higher definition has also been required for the developing method of the printer device. In addition, with the advancement of high functionality and digitalization of copiers, high resolution and high definition have been required similarly to printer devices.

[0005] To meet these demands, development systems have been improved.

On the other hand, non-magnetic one-component developing systems have been widely studied in order to achieve a cheaper electrophotographic system. Since this method does not require a carrier material that is essential for a two-component developing apparatus, the cost of the main body can be easily reduced, and a more inexpensive electrophotographic system is possible.

[0007] On the other hand, there are various developing methods in the developing method, and when roughly classified, two types, namely, jumping development and contact development, are representative. In the jumping development, the electrostatic latent image carrier and the developer carrier come close to each other with a very small space, and the developer flies under an alternating current and a direct current electric field, and the toner adheres to the latent image to perform the development. It is something to be done. Therefore, in the jumping development, the amount of toner to be developed for the line latent image is large, and there is a limit to high definition of the image.

On the other hand, in the contact developing method, the electrostatic latent image carrier and the toner on the developer carrier come into contact with each other, and the toner is subjected to an electric field and adheres to the latent image portion to perform development. . Therefore, development more faithful to the line latent image can be performed than jumping development, and it is easy to achieve the demand for higher resolution and higher definition.

In the charging system for primary charging of the electrostatic latent image carrier, an ozone-less charging system is preferably used due to increasing interest in office environments. In such a charging method, a regular developing method using a positive toner by a wire type corona discharge, or a contact charging method in which a member is brought into contact with an electrostatic latent image carrier to perform charging is used. In particular, the contact charging method has a possibility of simplifying the apparatus and using a DC power supply, and is suitably used in a developing method in which cost is suppressed.

On the other hand, the demand for color documents from the market is increasing, and the demand for color documents is increasing. There are various well-known methods for forming a full-color image by electrophotography, but most of them are formed by superimposing a plurality of color toners on an intermediate transfer body or a transfer material with each color toner such as yellow, magenta, cyan, and black. An image is synthesized and fixed on a recording material by heat and pressure fixing.

In such a full-color image forming method, it is required to maintain more appropriate charging characteristics and developing characteristics of the toner and charging characteristics of the electrostatic latent image carrier than a black monochromatic system. .

In recent years, miniaturization of a full-color image forming apparatus has been studied, but for that purpose it is necessary to reduce the size of a developing device. In order to reduce the size of the full-color image forming apparatus, it is necessary to reduce the size of a developing device that contains a cyan developer, a yellow developer, a magenta developer, and a black developer.

In reducing the size of the developing device, a non-magnetic one-component developing device is advantageous for the reasons described above. However, in the case of the non-magnetic one-component developing method, since the toner is charged by contact with the developer carrying member and the developer regulating member, it is required that such toner minimize the contamination of the developing system. Is done. For example, in a toner in which the developing system is contaminated, a layer of a contaminant is easily formed under the developer carrying member, and the layer of the contaminant hinders the triboelectric charging of the toner and gives the toner a charge. Insufficiency is not preferable because it induces development defects such as image fogging. Further, toner that contaminates such a developing system generally tends to adhere to the surface of the developer regulating member, and the adhered substance induces streak-like irregularities on the toner carrier when regulating the developer. ,
In particular, it is not preferable because it appears as a streak-like image defect on an image having a high printing rate. In particular, in a full-color image, since two colors of toner are superimposed to express a color, such a streak-like image defect appears on the image as a line having a different color, and the defect tends to be conspicuous, which is not preferable.

In particular, in a roller-type contact charging system, the toner contaminating the developing system as described above tends to cause contaminants to adhere to the surface of the charging roller. If the amount of contaminants adhered to the charging roller increases due to long-term printing or the like, the charging of the electrostatic latent image carrier is hindered, and the primary charging of the electrostatic latent image carrier becomes uneven. . If the primary charging of the electrostatic latent image carrier is not uniform, it is not preferable because unevenness of charging of the electrostatic latent image is visualized as an image during development and appears in the image as an image defect.

Further, the toner contaminating the developing system as described above tends to adhere to the electrostatic latent image carrier and easily cause fusion or filming to the electrostatic latent image carrier.
Such fusion and filming to the electrostatic latent image carrier is
This is undesirable because it appears in the image as an image defect.

Therefore, a proposal has been made in which the amount of liberated hydrophobic silica is specified as a toner which does not cause development trouble such as toner contamination and toner sticking to a developer carrier and a latent image carrier.

Specifically, JP-A-4-145448, JP-A-6-258864, JP-A-7-043
No. 931 proposes a toner in which hydrophobic silica is partially adhered to the toner surface and partially released. However, although these publications describe the amount of free silica and the amount of alumina, there is no description about compounds containing magnesium, especially hydrotalcite compounds, and also the release rate of compounds containing magnesium. There is no description.

In Japanese Patent Application Laid-Open No. 6-342224, the liberation rate of Si atoms with respect to the base toner is 0.5 to 20.
% Toner is disclosed. JP 2000
Japanese Patent Application No. 0-47425 discloses a toner in which the external additive released from the base particles is 5% or less of the whole toner. In these publications, although a toner in which the release rate of an external additive is limited using a particle analyzer is proposed, the release rate of a compound containing a magnesium element, particularly the release rate of a hydrotalcite compound, is described. Absent.

Further, Japanese Patent Application Laid-Open No. 2000-47418 discloses a toner for defining the external additive concentration using a particle analyzer. In this publication, the concentration of the toner not synchronized with the base particles is defined by the measurement result of the particle analyzer, and magnesium oxide is exemplified as an external additive. However, the fixed state of the external additive,
In particular, there is no description suggesting the BET specific surface area of the externally added toner, and there is no description about hydrotalcite compounds.

[0020]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner and an image forming method which solve the above-mentioned problems of the prior art.

That is, an object of the present invention is to provide a toner using an external additive containing a Mg element so that the state of the external additive attached to the toner particle surface is set within an appropriate range for measuring the BET specific surface area. It is another object of the present invention to provide a toner and an image forming method capable of suppressing fluctuations in the charging characteristics of a toner during durability and capable of always obtaining a stable image.

It is a further object of the present invention to minimize toner fusion and filming on the latent image carrier due to free external additives.
An object of the present invention is to provide a toner and an image forming method capable of forming a stable image for a long period of time.

It is a further object of the present invention to provide a toner and an image forming method which do not contaminate a charging member in a contact charging method and whose charging characteristics of a drum are durable and do not change.

[0024]

Means for Solving the Problems In order to achieve the above object, the present inventors have made intensive studies and as a result have come to disclose the present invention.

That is, the present invention relates to a toner in which fine particles containing Mg are externally added to colored particles containing at least a binder resin and a colorant.
And the percentage of free atoms or more and 10% or less 0.001%, BET value specific surface area of the toner is 0.5 m ² / g or more 30 m ² /
g or less.

Further, the present invention is a toner in which fine particles containing Mg are externally added to colored particles containing at least a binder resin and a colorant, wherein the free ratio of Mg atoms to carbon atoms is zero. 0.001% or more and 10% or less, and the BET specific surface area of the toner is 0.5 m ² / g or more and 30 m ² / g or less. The present invention relates to a toner which is a hydrotalcite compound represented by the formula (1).

[0027]

Embedded image (Where 0 <[X = (x1 + x2 +... + Xk)] ≦ 0.
5, Y = (y1 + y2 +... + Yj) = 1−X, j
And k are integers of 2 or more, M2, M3,.
L2, L3... and L different from each other selected from the group consisting of n, Ca, Ba, Ni, Sr, Cu and Fe.
k is a different metal selected from the group consisting of B, Ga, Fe, Co, and In, and ^An- represents an n-valent anion, and m ≧ 0. )

Further, according to the present invention, at least the image carrier is charged.
Charging; and forming an electrostatic latent image on the charged image carrier.
Forming an electrostatic latent image on a toner carrier;
Developed with the held toner, and a toner image is placed on the image carrier.
Developing step of forming; intermediately transferring the toner image on the image carrier
Transfer process that transfers to a transfer material with or without a photoreceptor
And a fixing step of fixing the toner image on the transfer material.
In the image forming method, the toner may include at least a binder tree.
Colored particles containing fat and a coloring agent contain fine particles containing Mg.
It is a toner with externally added powder,
The release rate of Mg atoms is 0.001% or more and 10% or less
The BET value specific surface area of the toner is 0.5 m ^Two/ G or more 3
0m^Two/ G or less.
Is achieved.

The present invention further provides a charging step for charging at least the image carrier; a latent image forming step for forming an electrostatic latent image on the charged image carrier; and carrying the electrostatic latent image on the toner carrier. Developing with the applied toner to form a toner image on the image carrier; and transferring the toner image on the image carrier to a transfer material with or without an intermediate transfer member. An image forming method having a fixing step of fixing a toner image on a transfer material, wherein the toner is represented by toner particles containing at least a binder resin and a colorant, an inorganic fine powder, and the general formula (1); A toner containing at least a hydrotalcite-based compound, wherein the liberation rate of Mg atoms with respect to carbon atoms of toner base particles is 0.001% or more and 10% or less, and the BET specific surface area of the toner is 0.5% or less.
an image forming method, wherein m ² / g or more 30 m ² / g or less.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies by the present inventors, the present invention relates to a toner obtained by externally adding a fine powder containing Mg to colored particles containing at least a binder resin and a colorant, 0.001% of free Mg atoms to carbon atoms
It has been found that the object of the present invention is achieved by a toner characterized in that the toner has a BET specific surface area of 0.5 m ² / g or more and 30 m ² / g or less.

Further, the present inventors have found that a toner in which the fine powder is a hydrotalcite compound represented by the following general formula (1) more preferably achieves the object of the present invention.

[0032]

Embedded image (Where 0 <[X = (x1 + x2 +... + Xk)] ≦ 0.
5, Y = (y1 + y2 +... + Yj) = 1−X, j
And k are integers of 2 or more, M2, M3,.
L2, L3... and L different from each other selected from the group consisting of n, Ca, Ba, Ni, Sr, Cu and Fe.
k is a different metal selected from the group consisting of B, Ga, Fe, Co, and In, and ^An- represents an n-valent anion, and m ≧ 0. )

Hereinafter, the configuration of the present invention will be described in detail.

First, in the toner of the present invention, the release ratio of Mg atoms to carbon atoms needs to be in the range of 0.001% to 10%, preferably 0.01% to 2%.

Although the details are unknown, the addition of a compound containing Mg to the toner improves the charging characteristics of the toner and enables stable image formation. In particular, the hydrotalcite compound is particularly preferable when used in combination with a negatively chargeable toner. This is an external additive having a polarity opposite to the chargeability of the toner. By using such an external additive, the charge amount distribution of the toner can be narrowly and uniformly charged. This is presumed to be due to the fact that the positively chargeable hydrotalcite compound is selectively electrostatically attached to the portion of the toner particles having a too high negative property to neutralize the charge.

In the toner charging in the one-component contact development, it is considered that the toner is charged by friction between the toner regulating member and the toner particles and between the developer carrier and the toner particles. It has been speculated that a mechanism in which the toners are mutually charged due to the friction of the toner. When two toner particle models are considered in such a mutual charging mechanism of a toner, it is considered that one is charged to a strong negative polarity and the other is charged to an opposite polarity.

It has been confirmed that a toner containing a hydrotalcite compound has a narrow charge amount distribution even in one-component contact development and is uniformly charged.

This is because the toner containing the hydrotalcite compound has a negative component derived from the toner base and a positive component derived from the hydrotalcite compound on the toner particles, and the toner also has a charging mechanism. This is considered to mean that an appropriate negative property is imparted to both toner particles.

However, as a result of further investigation, it was found that the toner containing the hydrotalcite compound
It has been clarified that the liberated hydrotalcite compounds easily contaminate the toner regulating member and the charging member of the electrostatic latent image carrier due to their charging characteristics, and cause image defects in durability.

Therefore, as a result of intensive studies, the rate of release of hydrotalcite compounds was limited to an appropriate range,
In addition, the inventors have found that the above problem can be solved by optimizing the state of the external additive attached to the toner surface, and have reached the present invention.

In order to keep the release rate of Mg atoms within an appropriate range, a known external addition method can be used. Preferably, a hydrotalcite compound containing an Mg atom is stirred at high speed by a known external addition means and sufficiently mixed, and then a fluidity improver such as silica fine powder is added, and the mixture is stirred at high speed and thoroughly mixed. External attachment can be used.

By externally adding in two stages as described above, the adhesion state of the hydrotalcite compound is uniform and Mg is added.
It is possible to obtain a toner having an atomic release rate in a suitable range.

In addition, when the external addition is performed in two stages as described above, the stirring and mixing conditions of pre-stirring and post-stirring may be adjusted.
It is preferable to obtain a toner having a g atom release ratio in a suitable range.

The stirring and mixing conditions for pre-stirring and post-stirring are as follows:
The strength of the stirring energy and the length of the stirring time vary. The low-speed stirring used in this example is a state in which the stirring energy in high-speed stirring is about 1/2 and the stirring time is 3/4 of the stirring time in high-speed stirring.

The stirring method suitable for producing the toner of the present invention is not particularly limited as long as it is mechanically attached to the outside, and can be carried out using a known stirring device. Preferably, a Henschel mixer or a homogenizer is used, and more preferably, a Henschel mixer can be used.

The method of measuring the liberation ratio of Mg atoms to carbon atoms of toner base particles is based on the following analysis method of toner.
Electrophotography Society Annual Conference (95 times in total), “Japan
Hardcopy '97, "A New Method of External Addition Evaluation-Toner Analysis Using a Particle Analyzer-" (Toshiyuki Suzuki, Toshio Takahara, sponsored by the Society of Electrophotography, July 9-11, 1997) Can be performed.

In this toner analysis method, toner particles are excited by introducing the toner particles into plasma, and an analysis is performed by detecting an emission spectrum accompanying the excitation.

According to this analysis method, it is possible to simultaneously detect the emission spectrum accompanying the excitation of a plurality of elements.
Further, the periodicity of the emission spectrum can be measured.

As a method for determining the release rate of the external additive, synchronism was used.

The elements contained in the same particle generate an excitation emission spectrum (synchronous spectrum) at the same period, while the element existing as a single substance such as a free substance of the external additive does not synchronize with the toner base. Produces an excited emission spectrum (asynchronous spectrum) by itself. By determining asynchronously / synchronously the excitation emission spectrum derived from each of these elements quantitatively, the release rate of the specific element from the toner base was determined.

In the present application, the synchronization spectrum is calculated based on the synchronization difference between the emission spectrum associated with the excitation of carbon atoms originating from the base particles and the excitation spectrum associated with the excitation of Mg atoms originating from an external additive such as a hydrotalcite compound. The atoms that have not been used are taken as free external additives, and the ratio is defined as the release rate of the external additives.

As a specific measuring method, Yokogawa Electric Corporation
The measurement was performed using PT1000 manufactured under the following conditions, and then the emission rate was determined by applying the synchronization of the emission of Mg atoms with respect to the C atoms to the following equation.

<< Measurement conditions of PT1000 manufactured by Yokogawa Electric Corporation >> Number of C atoms detected in one measurement: 500 to 2500 ・ Noise cut level: 1.5 or less ・ Sort time: 20 digits ・ Gas: O ₂ 0.1%, He gas-Analysis wavelength: C atom: 247.860 nm Mg atom: 285.210 nm-Channel used: C atom: 1 or 2 Mg atom: 1 or 2-Release rate of Mg atom (with C atom Count of Mg atoms that did not emit at the same time) / (Count of Mg atoms that emitted at the same time as C atoms + number of Mg atoms that did not emit at the same time as C atoms) x 100

In the toner of the present invention, controlling the surface of the toner so that the BET specific surface area of the toner is 0.5 m ² / g or more and 30 m ² / g or less in terms of charge stability, developability and transferability. Required, and preferably 0.5 m ² / g or more and 10 m ² or more.
/ G or less.

The BET specific surface area of the toner is 0.5 m ² / g
If it is more than the above, the charging characteristics and transferability are insufficient, and 30
If it exceeds mm ² / g, the fluidity and developability of the toner will decrease.

The specific surface area of the toner in the above range can be achieved by controlling the specific surface area of the toner particles and the specific surface area, amount and mixing strength of the inorganic fine powder added to the toner particles.

The specific surface area was measured by adsorbing nitrogen gas according to the BET method. Specifically, it is based on the following conditions.

Measuring device: Specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics) Sample amount: about 2 g Adsorbed gas: nitrogen Calculation method: BET multipoint method

Examples of the fine powder containing Mg that can be used in the present invention include hydrotalcite compounds of natural minerals. These may preferably be those subjected to a surface treatment with a treating agent such as a higher fatty acid.

The hydrotalcite compounds that can be suitably used in the present invention are compounds having a composition represented by the following general formula (1).

[0061]

Embedded image (Where 0 <[X = (x1 + x2 +... + Xk)] ≦ 0.
5, Y = (y1 + y2 +... + Yj) = 1−X, j
And k are integers of 2 or more, M2, M3,.
L2, L3... and L different from each other selected from the group consisting of n, Ca, Ba, Ni, Sr, Cu and Fe.
k is a different metal selected from the group consisting of B, Ga, Fe, Co, and In, and ^An- represents an n-valent anion, and m ≧ 0. )

In the general formula (1), it is more preferable that the divalent metal and the trivalent metal satisfy the following relationship. y1> y2 +... + yj, more preferably, y1> 10 ×
(Y2 + ... + yj) x1> x2 + ... + xk, more preferably x1> 10x
(X2 +... + Xk), particularly x1> 20 × (x2 +.
xk)

Further, it is preferable to satisfy 0.9 ≦ x1 + y1 <0.1, and 0.930 ≦ x1 + y1 ≦ 0.9
It is more preferable that the ratio satisfies 98.

The content (atomic ratio) of divalent metals other than Mg is preferably 0.001 ≦ y2 +... + Yj ≦ 0.05, and the content (atomic ratio) of trivalent metals other than Al is preferably It is preferable to satisfy 0.0003 ≦ x2 +... Xk ≦ 0.02.

When a divalent metal other than Mg and a trivalent metal other than Al are contained in the above ranges, the effect of the present invention of improving the charging stability becomes remarkable.
When the content of the divalent metal other than Mg and the content of the trivalent metal other than Al exceeds the above range, the effect relating to the charging stability decreases, and when the content is less than the above range, the environmental stability and The storage stability is likely to be inferior.

The hydrotalcite compounds are represented by M
More preferably, Ca is contained as a divalent metal other than g, and as the trivalent metal, B, G contained
The total amount of e, Fe, and Ga is 0.0003 to
More preferably, it is 0.02.

The hydrotalcite compounds used in the present invention include, as A ⁿ⁻ (n-valent anion), CO ₃ ^2- ,
^{OH -, Cl -, I -} , F -, Br -, SO 4 -, HCO 3 -,
CH ₃ COO ⁻ and NO ₃ ⁻ are exemplified, and a single compound or a plurality of compounds may be present.

The hydrotalcite compound preferably has water in the molecule, and more preferably 0.1 <m <0.6 in the general formula (1).

Specific examples of hydrotalcite compounds suitable in the present invention include hydrotalcite compounds A to H represented by the composition formulas shown in Table 1 below. In addition, the symbol described in the present exemplary compound and the symbol in this example are common.

[0070]

[Table 1]

The amount of the hydrotalcite compound used in the present invention is preferably from 0.1 to 5 parts by mass, more preferably from 0 to 5 parts by mass, based on 100 parts by mass of the colored particles, from the viewpoint of electrophotographic characteristics and transparency. .2 to 3 parts by weight can be used.

In addition to the hydrotalcite compounds, there may be mentioned inorganic oxides such as magnesium oxide, magnesium phosphate, magnesium carbonate and magnesium sulfate, and natural minerals such as magnetite powder. Those which have been subjected to a surface treatment with a treating agent such as a higher fatty acid can be preferably used.

In the toner of the present invention, in addition to the fine powder containing Mg, the following known inorganic powders may be used for the purpose of improving charge stability, developability, fluidity and durability. preferable.

Examples of the inorganic powder include oxides of metals such as silicon, zinc, aluminum, cerium, cobalt, iron, zirconium, chromium, manganese, strontium, tin, and antimony; calcium titanate, magnesium titanate, and strontium titanate. Metal salts such as calcium carbonate, magnesium carbonate and aluminum carbonate; clay minerals such as kaolin; phosphoric acid compounds such as apatite; silicon compounds such as silicon carbide and silicon nitride; carbon such as carbon black and graphite. Powder.

Of these, fine powders of silicon dioxide, zinc oxide, aluminum oxide, cobalt oxide, manganese dioxide, strontium titanate, and magnesium titanate are preferred, and are treated with silicone oil or a coupling agent, or with a treating agent such as a higher fatty acid. Those subjected to a surface treatment can be preferably used. Specific examples include fine silica powder that has been hydrophobicized by silicone oil treatment, titanium oxide that has been hydrophobicized by silicone oil treatment, and alumina that has been hydrophobicized by silicone oil treatment. Silicone oil treated silica fine powder preferably used in the present invention has a specific surface area by nitrogen adsorption measured by BET method is 20 m ² / g or more (especially 30 to 400 m ²
/ G).

Specific examples of the silicone oil include silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane coupling agents, silane coupling agents having a functional group, and other organosilicon compounds. These treating agents may be used alone or in combination.

Further, a known lubricant powder may be added to the toner. Examples of the lubricant powder include known resin particles such as polystyrene, polymethyl methacrylate, and polycarbonate; fluorine resins such as Teflon (registered trademark) and polyvinylidene fluoride; fluorine compounds such as carbon fluoride; and fatty acid metal salts such as zinc stearate. Fatty acid derivatives such as fatty acids and fatty acid esters; and molybdenum sulfide.

The amounts of the known inorganic powder and lubricant powder used in addition to the Mg-containing fine powder used in the present invention are as follows:
From the viewpoints of electrophotographic characteristics and transparency, 0.5 to 7 parts by mass, more preferably 1.0 to 3.0 parts by mass can be used based on 100 parts by mass of the colored particles.

The binder resin used in the toner of the present invention is
There is no particular limitation as long as it is used when producing a toner.

Specific examples of the binder resin used in the toner of the present invention include polymers of the following polymerizable monomers, a mixture of polymers of a single polymerizable monomer, and two or more kinds of polymers. And copolymerization products of polymerizable monomers. More specifically, a styrene-acrylic acid copolymer or a styrene-methacrylic acid copolymer is preferred.

Examples of the styrene polymerizable monomer include styrene, o-methylstyrene, m-methylstyrene,
p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert Styrene such as -butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene and pn-dodecylstyrene, and derivatives thereof.

Examples of the acrylate-based polymerizable monomers include methyl methacrylate, ethyl methacrylate,
Propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate,
Α-methylene aliphatic monocarboxylic esters such as stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, acrylic Acrylates such as propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, and derivatives thereof.

In order to obtain the binder resin used in the present invention, it is preferable to use a polymerization initiator as exemplified below.

Specifically, examples of the peroxide-based initiator include t-butyl peroxy-2-ethylhexanoate, cumin perpivalate, t-butyl peroxy laurate, benzoyl peroxide, lauroyl peroxide. Oxide, octanoyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide,
1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, n-butyl 4,4-bis (t
-Butylperoxy) valerate, dicumyl peroxide and the like and derivatives thereof.

Examples of azo and diazo initiators include 2,2′-azobisisobutyronitrile, 1,1-
Azobis (cyclohexane-1-carbonitrile),
2,2′-azobis (2-methylbutyronitrile),
Examples include 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), and derivatives thereof.

These polymerization initiators may be used alone or in combination of two or more. The amount used is 0.05 parts by mass to 15 parts by mass per 100 parts by mass of the polymerizable monomer.
It is used in a concentration of 0.5 parts by mass, more preferably 0.5 parts by mass to 10 parts by mass.

As the colorant that can be used in the toner of the present invention, conventionally known inorganic and organic dyes and pigments can be used. Specific examples include the following.

Specific examples of the yellow color pigment include compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds and allylamide compounds. More specifically, C.I. I. Pigment Yellow 1, 2, 3, 4,
5, 6, 7, 10, 11, 12, 13, 14, 15, 1
6, 17, 23, 65, 73, 83, 93, 94, 9
5, 97, 109, 110, 111, 120, 127,
128, 129, 147, 168, 174, 176, 1
80, 181, 191, C.I. I. Bat Yellow 1,
3, 20 and the like. In addition, graphite, cadmium yellow, mineral fast yellow, navel yellow,
Naphthol yellow S, Hansa yellow G, permanent yellow NCG, tartrazine lake and the like can also be used.

Specific examples of the color pigment for magenta include:
C. I. Pigment Red 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, 14, 15, 1
6, 17, 18, 19, 21, 22, 23, 30, 3
1,32,37,38,39,40,41,48,4
9, 50, 51, 52, 53, 54, 55, 57, 5
8,60,63,64,68,81,83,87,8
8, 89, 90, 112, 114, 122, 123, 1
63, 202, 206, 207, 209, C.I. I. Pigment Violet 19, C.I. I. Bat Red 1,
2, 10, 13, 15, 23, 29, 35 and the like.

Further, as the dye, C.I. I. Solvent red 1,3,8,23,24,25,27,30,
49, 81, 82, 83, 84, 100, 109, 12
1, C.I. I. Disperse Red 9, C.I. I. Oil-soluble dyes such as Disperse Violet 1, C.I. I. Basic Red 1,2,9,12,13,14,15,17,1
8, 22, 23, 24, 27, 29, 32, 34, 3
Basic dyes such as 5,36,37,38,39,40,
C. I. Acid Red 1, C.I. I. Direct Red 1, 4, C.I. I. Modant Red 30 and the like.

Specific examples of the cyan color pigment include C.I.
I. Pigment Blue 2, 3, 15, 16, 17, C.I.
I. Basic Blue 3, 5, C.I. I. Bat Blue 6, C.I. I. Direct Blue 1, 2, C.I. I. Acid blue 9, 15, 45, C.I. I. Modant Blue 7 or copper phthalocyanine pigment.

Specific examples of the black coloring pigment include carbon black, alinine black, acetylene black, oil black and the like. Also, mix colorant for color,
It is also possible to use as a black colorant.

Further, in addition to the above coloring agents, titanium white, C.I. I. Direct Green 6, C.I. I. Basic Green 4, 6, Pigment Green B, Malachite Green Lake, Final Yellow Green G, Chrome Green, Molybdenum Orange, Permanent Orange GTR, Pyrazolone Orange, Benzidine Orange G, C.I. I. Basic violet 1,3,7,1
0, 14, 15, 21, 25, 26, 27, 28, C.I.
I. Solvent Violet 8,13,14,21,2
7, manganese purple, fast violet B, methyl violet lake, and the like can be used as a colorant for a toner other than the above colors.

These can be used alone or in combination. Usually, based on 100 parts by mass of the binder resin,
It is used in an amount of 0.1 to 60 parts by mass, preferably 0.5 to 20 parts by mass.

The colorant as described above can be used as a toner for forming a full-color image by a multicolor developing method.

The toner of the present invention has charge stability, developability,
It is preferable to control the shape for the purpose of improving transferability and fluidity.

Methods for controlling the shape of the toner include a method of mechanically spheroidizing the pulverized toner, a method of spheroidizing irregularly shaped toner particles in an atmosphere at or above the glass transition temperature of the toner binder, a suspension polymerization method, and the like. Known methods such as a method of producing a toner by an emulsion polymerization method and a method of aggregating resin fine particles having a particle size equal to or less than the toner particle size and solidifying the toner particle size can be used.

The preferable range of the shape control in the toner of the present invention is that the average circularity of the toner is 0.1 in the circle equivalent diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring apparatus. 920-0.9
At 95, the circularity standard deviation is 0.040 or less.

The toner having an average circularity of 0.920 or less means a toner whose shape has moved away from a spherical shape and approached an irregular shape. Such an irregular toner tends to be crushed in the developing device during development, so that the particle size distribution fluctuates and the charge amount distribution becomes broad, and as a result, image density decreases and fog is reduced. This is not preferable because an inconvenient phenomenon such as increase in development is likely to occur.

The toner having an average circularity of 0.995 or more means a true spherical toner. Such a spherical toner is excellent in chargeability and transferability, but generally tends to cause cleaning failure by cleaning means such as blade cleaning, and the residual toner remaining on the latent image carrier after development is removed by a blade cleaning mechanism. It is not preferable because it is difficult to remove, and as a result, an inconvenient development phenomenon such as an image defect due to poor cleaning or an image defect due to interference with charging and exposure is likely to occur.

The circle equivalent diameter, circularity and frequency distribution of the toner in the present invention are used as a simple method for quantitatively expressing the shape of the toner particles. In the present invention, the flow type particle image measurement is used. The measurement was performed using an apparatus FPIA-1000 (manufactured by Toa Medical Electronics Co., Ltd.), and calculated using the following equation.

[0102]

(Equation 1)

Here, the “particle projection area” is the area of the binarized toner particle image, and is the “perimeter of the particle projection image”.
Is defined as the length of the contour obtained by connecting the edge points of the toner particle image.

In the present invention, the circularity is an index indicating the degree of unevenness of the toner particles. When the toner particles are perfectly spherical, the circularity is 1.00. Become.

In the present invention, the circle-equivalent number average diameter and the standard particle diameter SDd, which mean the average value of the number-based toner particle size frequency distribution, are the particle size (central value) at the dividing point i of the particle size distribution.
Where di is the frequency and fi is the frequency.

[0106]

(Equation 2)

Further, the average circularity and the circularity standard deviation SDc, which mean the average value of the circularity frequency distribution, are as follows, where the circularity (center value) at the dividing point i of the particle size distribution is ci and the frequency is fci. It is calculated from the formula.

[0108]

(Equation 3)

As a specific measuring method, 10 ml of ion-exchanged water from which impure solids and the like have been removed in advance is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersing agent thereto. Then, about 0.02 g of a measurement sample is further added, and the mixture is uniformly dispersed. As a means for dispersing, an ultrasonic dispersing machine UH-50 type (manufactured by SMT Corporation) equipped with a titanium alloy chip of 5φ as a vibrator is used, and a dispersion treatment for 5 minutes is used to prepare a dispersion for measurement. At this time, the dispersion is appropriately cooled so that the temperature of the dispersion does not become 40 ° C. or higher.

For the measurement of the shape of the toner particles, the above-mentioned flow type particle image measuring device was used.
The concentration of the dispersion liquid is readjusted so as to be 00 to 15000 particles / μl, and 1,000 or more toner particles are measured. After the measurement, using this data, the equivalent circle diameter and circularity frequency distribution of the toner are obtained.

In order to achieve higher image quality, it is necessary to faithfully develop finer latent image dots. In order to achieve high image quality in the present invention, the equivalent circle diameter of the toner particles is preferably 3 to 10 μm, and the equivalent circle diameter is 5 μm.
More preferably, it is 8 μm.

In the case of toner particles having an equivalent circle diameter of less than 3 μm, the photosensitive member is used as an intermediate transfer member, the intermediate transfer member is used as a recording material,
Transfer efficiency of toner particles from the photoreceptor to a recording material or the like is reduced, and adhesion of untransferred residual toner causes image defects, which is not preferable for the toner used in the present invention. Further, such toner tends to cause non-uniform unevenness of an image due to fogging and transfer failure, and is not preferable for the toner used in the present invention. Further, the equivalent circle diameter of the toner particles is 10 μm.
If it exceeds m, scattering of characters and line images is likely to occur, and it is difficult to reproduce minute dots for high image quality, which is not preferable.

Further, in the present invention, in order to always obtain a stable image during the running, the amount of the fine powder in the toner is reduced to 50% by number.
It is preferable to set the following. When the amount of the fine powder in the toner is 50% by number or more, the toner particle diameter consumed during the durability becomes easy to be selectively developed, the particle size distribution in the toner in the latter half of the durability greatly fluctuates, and the charging characteristics of the toner become poor. It fluctuates and induces image defects such as fogging and poor transfer, which is not preferable.

In the present invention, the amount of fine powder in the toner means the number% of toner particles in the range of 0.6 to 3.0 μm in the number-based particle size distribution of toner particles measured by a flow type particle image measuring device. It is.

Further, when the toner of the present invention is used in combination with a non-magnetic one-component contact developing system, it is important to maintain the mechanical strength of the toner. When the mechanical strength of the toner is weak, it is preferable because the toner is crushed and deformed, or chipped to generate fine powder, adheres to the developer carrying member or the developer regulating member, and induces image defects such as image streaks. Absent.

In order to keep the hardness of the toner constant and maintain the stress resistance, it is preferable to define the crosslinkable resin component of the toner.

Therefore, as a method of quantitatively expressing the cross-linking component of the toner, it is preferable to define the range of the component substantially insoluble in the tetrahydrofuran solvent.

The component substantially insoluble in the tetrahydrofuran solvent contained in the toner of the present invention is preferably contained in an amount of 1 to 50% by mass, more preferably 5 to 40% by mass, based on the whole toner. Is more preferable.

When the content of the component substantially insoluble in the tetrahydrofuran solvent contained in the toner is 1% by mass or less, the toner particles are easily deformed by the stress applied to the toner during the contact development. Therefore, such a toner is not preferable because the toner easily fuses to the regulating member.

On the other hand, when the content of the component substantially insoluble in the tetrahydrofuran solvent contained in the toner is 60% by mass or more, the melting property of the toner binder is changed, and especially when a full-color image is output, other colors may be used. For example, color mixing with cyan and magenta is deteriorated, and a problem that a delicate color cannot be reproduced occurs, which is not preferable.

A specific example of the method for measuring the THF insoluble content in the present invention is shown below.

Resin or toner sample 0.5 to 1.0 g
Is weighed (W ₁ g), placed in a thimble filter paper (for example, No. 86R manufactured by Toyo Roshi Kaisha), passed through a Soxhlet extractor, and extracted with 100 to 200 ml of THF as a solvent for 6 hours. After evaporation, 1
After vacuum drying at 00 ° C. for several hours, the amount of the THF-soluble resin component is weighed to obtain (W ₂ g). Further, the mass of an insoluble component other than the resin component such as a pigment is measured and defined as (W ₃ g).

The THF-insoluble content is obtained from the following equation.

[0124]

(Equation 4)

To adjust the components substantially insoluble in the tetrahydrofuran solvent contained in the toner of the present invention,
It is preferable to contain a crosslinkable polymerizable monomer exemplified below.

As the crosslinkable polymerizable monomer, mainly 2
Polymerizable monomer pairs having at least two polymerizable double bonds are used.

As specific examples, bifunctional crosslinking agents such as divinyl compounds such as divinylbenzene, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, and polyethylene glycol # 200, # 40
Examples thereof include diacrylates such as 0 and # 600, and those obtained by replacing the above acrylates with methacrylate.

As polyfunctional crosslinking agents, pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, oligoester acrylate and its methacrylate, 2,2-bis (4-methacryloxy, Ethoxyphenyl) propane, diallyl phthalate, triallyl cyanurate,
Triallyl asocyanurate, triallyl isocyanurate, triallyl trimellitate, diarylchlorendate and the like.

Among these crosslinking polymerizable monomers, those preferably used include aromatic divinyl compounds (particularly divinylbenzene) and diacrylate compounds linked by a chain containing an aromatic group and an ether bond. .

In order that the components substantially insoluble in the tetrahydrofuran solvent contained in the toner of the present invention are contained in an amount of 1 to 60% by mass based on the total amount of the toner, these crosslinking agents may be used in combination with other polymerization agents. It is preferable to use about 0.01 to 5 parts by weight, more preferably 0.03 to 3 parts by weight, based on 100 parts by weight of the monomer component.

In the molecular weight distribution of the component soluble in the tetrahydrofuran solvent of the toner according to the present invention measured by GPC, the number average molecular weight (Mn) is 8,000.
~ 30,000 and a weight average molecular weight (Mw) of 50
It is preferably from 000 to 500,000. Number average molecular weight (Mn) is 8000 or less and weight average molecular weight (M
A toner having w) of 50,000 or less has a problem in that a toner blocking phenomenon occurs in which toner particles are fused and aggregated by heat under a condition that can be assumed as a storage environment. On the other hand, the number average molecular weight (Mn) is 300
00 or more and the weight average molecular weight (Mw) is 500000
The above toner is not preferable because it becomes difficult to achieve good fixability particularly in the development in which multiple colors such as full colors are superimposed.

The resin used in the present invention has a ratio (Mw / Mw) between the weight average molecular weight (Mw) and the number average molecular weight (Mn).
Mn) is preferably from 2 to 100 from the viewpoints of fixability and print quality.

The molecular weight of the toner of the present invention is measured by GPC (gel permeation chromatography). As a specific GPC measurement method, a sample obtained by extracting a toner in advance with a THF (tetrahydrofuran) solvent using a Soxhlet extractor for 20 hours is used, and the column configuration is A-801, 802, 803, 8 manufactured by Showa Denko.
04, 805, 806, and 807 are linked, and the molecular weight distribution can be measured using a standard polystyrene resin calibration curve.

In the present invention, a known chain transfer agent may be added for the purpose of controlling the molecular weight.

Specific examples of the chain transfer agent include halogenated compounds such as carbon tetrachloride, carbon tetrabromide, ethyl dibromide acetate, ethyl oxybromide acetate, ethyl dibromide, ethane dibromide and ethane dichloride. Hydrocarbon compounds such as diazothioether, benzene, ethylbenzene and isopropylbenzene; mercaptan compounds such as tertiary decyl mercaptan and n-dodecyl mercaptan; disulfide compounds such as diisopropylzantogen disulfide; α-methylstyrene dimer Oligomers and the like.

The amount of the chain transfer agent to be added is generally 0.1 to achieve the purpose of controlling the molecular weight.
001 to 15 parts by weight are used.

Further, the toner of the present invention preferably contains a wax component in order to improve the releasability at the time of fixing.

Specific examples of the wax component include the following compounds.

For example, silicone resin, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin such as low molecular weight polyethylene or low molecular weight polypropylene, aromatic Group petroleum resin, chlorinated paraffin, paraffin wax and the like.

[0140] From these waxes, waxes obtained by fractionating waxes by molecular weight by various methods are also preferably used in the present invention. Further, after fractionation, acid value, block copolymerization and graft modification may be performed.

Of these, waxes preferably used are low-molecular-weight polypropylene and by-products of low-molecular-weight polyesters, low-molecular-weight polyesters and ester waxes, and aliphatic derivatives.

Among these, examples of more preferred representative compounds of the ester wax are shown below as general structural formulas of the ester wax.

[0143]

Embedded image (Where a and b represent an integer of 0 to 4, a + b is 4, R ₁ and R ₂ represent an organic group having 1 to 40 carbon atoms,
And a group in which the carbon number difference between R ₁ and R ₂ is 10 or more,
n and m each represent an integer of 0 to 15, and n and m do not become 0 at the same time. )

[0144]

Embedded image (Where a and b represent an integer of 0 to 4, a + b is 4, R ₁ represents an organic group having 1 to 40 carbon atoms, n and m each represent an integer of 0 to 15, n And m do not become 0 at the same time.)

[0145]

Embedded image (Where a and b each represent an integer of 0 to 3, a + b + k is 4, R ₁ and R ₂ each represent an organic group having 1 to 40 carbon atoms, and the carbon number of R ₁ and R ₂ is A group having a difference of 10 or more, R ₃ represents an organic group having 1 or more carbon atoms, n and m each represent an integer of 0 to 15, and n and m are not 0 at the same time.)

[0146]

Embedded image The general structural formula R ₁ COOR _{2 of the} ester wax (wherein R ₁ and R ₂ represent a hydrocarbon group having 1 to 40 carbon atoms, and R ₁ and R ₂ are the same or different. The carbon number may be used.)

[0147]

Embedded image The general structural formula of ester wax R ₁ COO (CH ₂ ) _n OOCR ₂ (wherein R ₁ and R ₂ represent a hydrocarbon group having 1 to 40 carbon atoms, and n is an integer of 2 to 20) And R ₁ and R ₂ are
They may have the same or different carbon numbers. )

[0148]

Embedded image General structural formula of ester wax R ₁ OOC (CH ₂ ) nCOOR ₂ (wherein R ₁ and R ₂ represent a hydrocarbon group having 1 to 40 carbon atoms, and n is an integer of 2 to 20) And R ₁ and R ₂ are
They may have the same or different carbon numbers. )

These waxes are generally used in an amount of 2 to 100 parts by mass of the toner in order to improve the releasability at the time of fixing.
30 parts by weight, more preferably 5 to 20 parts by weight are used. When the amount of the wax component is less than 2 parts by mass, the releasing effect as a wax can hardly be exhibited, and when the amount of the wax component exceeds 30 parts by mass, the releasability of the toner is satisfied, but the developing property of the toner is improved. Is worsened, and the adverse effect such as fusion of the toner to the developing sleeve and the surface of the latent image carrier is easily caused.

[0150] The wax component according to the present invention showed a 5% increase in temperature according to the DSC curve measured by a differential scanning calorimeter.
A maximum endothermic peak is shown in the range of 0 to 100 ° C., and the onset temperature of the starting point of the endothermic peak including the maximum endothermic peak is 4
0 ° C. or more, and particularly, a temperature difference between the peak temperature of the maximum endothermic peak and the onset temperature is 7 to 50 ° C.
Is preferably within the range.

In the DSC curve at the time of temperature rise, by using a wax component that melts in the above temperature range, the dispersibility of other additives can be improved, and
The wax component itself can be easily controlled to the dispersed state as described above.

As a result, the releasing effect of the wax component as well as the good fixing property of the toner is effectively exhibited, a sufficient fixing area is secured, and the developing property and the anti-blocking property of the conventionally known wax component are attained. These characteristics are significantly improved because the adverse effects on the performance and the image forming apparatus are eliminated. In particular, since the specific surface area of the toner decreases as the particle shape becomes spherical, it is very effective to control the dispersion state of the wax component.

In the DSC measurement of the present invention, since the exchange of heat of the wax is measured and its behavior is observed, it is preferable from the principle of measurement that the measurement be performed with a high-precision internal heat input compensation type differential scanning calorimeter. . For example, DSC-7 manufactured by PerkinElmer can be used.

The measuring method is described in “ASTMD3418-8.
2 ”. In the case of measuring only the wax component, the DSC curve used in the present invention is a DSC curve measured when the temperature is raised once and lowered once, a pre-history is taken, and then the temperature is raised at a temperature rate of 10 ° C./min. When the measurement is performed in a state where the toner is included in the toner, a DSC curve that is measured as it is without using a previous history is used.

In the present invention, known charge control agents can be used. Charge control agents include those that control the toner to be negatively charged and those that control the toner to be positively charged.

Examples of substances that control the toner to be negatively charged include the following substances.

For example, organic metal compounds and chelate compounds are effective, and specific examples include monoazo metal compounds, acetylacetone metal compounds, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid-based metal compounds. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol. Also, urea derivatives, metal-containing salicylic acid-based compounds, metal-containing naphthoic acid-based compounds, boron compounds, quaternary ammonium salts, calixarenes, silicon compounds, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers,
A styrene-acryl-sulfonic acid copolymer, a nonmetal carboxylic acid-based compound and the like can be mentioned.

Specific examples of the substance which controls the toner to be positively charged include the following substances.

For example, denatured products such as nigrosine and fatty acid metal salts, guanidine compounds, imidazole compounds,
Tributylbenzylammonium-1-hydroxy-4
Quaternary ammonium salts such as naphthosulfonate and tetrabutylammonium tetrafluoroborate, and onium salts such as phosphonium salts which are analogs thereof, and their lake pigments, triphenylmethane dyes and their lake pigments Examples of the agent include phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.), metal salts of higher fatty acids;
Dibutyltin oxide, dioctyltin oxide,
Diorganotin oxides such as dicyclohexyltin oxide; diorganotin borates such as dibutyltin borate, dioctyltin borate and dicyclohexyltin borate; and these can be used alone or in combination of two or more. Of these, charge control agents such as nigrosine and quaternary ammonium salts are particularly preferably used.

The glass transition point of the toner is determined by the polymerizable monomer,
The glass transition point Tg of the toner according to the present invention is preferably from 40 to 75 ° C, more preferably from 50 to 70 ° C, which is determined by a combination of a crosslinking agent, an initiator, polymerization conditions and the like. When the glass transition point Tg is lower than 40 ° C., the storage stability is deteriorated and blocking occurs during storage, which is not preferable. If the glass transition point Tg exceeds 75 ° C., it is necessary to increase the energy consumption of the fixing device in order to obtain a fixed material having a certain gloss, so that the power consumption is large, and the fixing heat energy is sufficient for the toner. Therefore, the fixing speed must be reduced, which causes a problem that printing at a general speed cannot be performed, which is not preferable.

The glass transition point Tg of the toner according to the present invention
For example, a Perkin Elmer DSC-
The measurement is performed with a high-precision internal heating type input compensation type differential scanning calorimeter such as 7. The measuring method is ASTM D3418-
Perform according to 82. In the present invention, the sample is heated once to obtain a pre-history, then rapidly cooled, and then cooled again to a temperature of 10 ° C.
/ Min, a DSC curve measured when the temperature is raised in the range of 0 to 200 ° C.

The method for producing the toner according to the present invention is not limited at all, and known methods such as a melt-pulverization method and a polymerization method can be used.

As an example of the melt pulverization method, a binder resin, a wax, a colorant, and other additives are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill.
Melting and kneading using a hot kneader such as a heating roll, kneader, extruder and the like to disperse or dissolve the metal compounds, pigments, dyes, and magnetic materials in the resin, then solidify by cooling, and then pulverize. By performing the classification, the developer according to the present invention can be obtained. In the classification step, it is preferable to use a multi-divider classifier in terms of production efficiency.

Examples of the method for producing the toner by the polymerization method include:
A polymerizable monomer, a crosslinking agent, a polymerization initiator, a wax, a colorant, and other additives are mixed and dispersed, and then subjected to suspension polymerization in an aqueous system in the presence of a suspension / dispersion stabilizer to polymerize and color. The developer according to the present invention can be obtained by synthesizing resin particles, performing solid-liquid separation, and drying and then classifying.

Specific examples of the suspension / dispersion stabilizer include:
For example, as inorganic oxides, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide,
Examples include magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina, a magnetic substance, and ferrite. As the organic compound, for example, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, starch and the like are used by being dispersed in an aqueous phase. It is preferable to use 0.2 to 10 parts by mass of these dispersants based on 100 parts by mass of the polymerizable monomer.

Hereinafter, an image forming method suitable for the present invention will be described.

In the step of charging the latent image carrier in the image forming method of the present invention, various charging methods can be used.

Specifically, a corona discharge in which the charging means is not in contact with the electrostatic latent image carrier or a direct charging method in which the charging member is brought into contact with the electrostatic latent image carrier can be suitably used. A direct charging method of contacting the electrostatic latent image carrier can be preferably used. In the case of the direct charging method, when a general toner is used, if residual toner after cleaning adheres to a direct charging member in a later process, poor charging is caused, and charging unevenness occurs on an image. Therefore, the amount of residual toner needs to be smaller and less likely to adhere as compared with corona discharge or the like in which the charging means does not contact the electrostatic latent image carrier. Therefore,
In the direct charging method, it is necessary to use a toner whose average circularity and circularity standard deviation are strictly defined.

Other charging methods include a method using a charging blade and a method using a conductive brush. These contact charging means, compared to non-contact corona charging,
There are effects that a high voltage becomes unnecessary and generation of ozone is reduced. The material of the charging roller and the charging blade as the contact charging means is preferably a conductive rubber, and a release coating may be provided on the surface thereof. As the release coating, a nylon resin, PVDF (polyvinylidene fluoride), PVDC (polyvinylidene chloride) or the like can be applied.

In the developing step in the image forming method of the present invention, the toner carrier and the surface of the electrostatic latent image carrier may be in non-contact or contact. More preferably, the toner carrier and the surface of the electrostatic latent image carrier are in contact with each other.

Further, the potential is controlled so that the residual toner on the electrostatic latent image carrier can be collected simultaneously with the development at the time of development. This is preferable because a significant reduction in size can be achieved.

As the toner carrier, a method of using an elastic roller, coating the surface of the elastic roller with a developer and bringing the developer into contact with the surface of the electrostatic latent image carrier is also used. In this case, development is performed by an electric field acting between the electrostatic latent image carrier and the elastic roller facing the surface of the electrostatic latent image carrier via the developer. Therefore, the surface of the elastic roller or the vicinity of the surface has a potential, and it is necessary to have an electric field in a narrow gap between the surface of the electrostatic latent image carrier and the surface of the toner. For this reason, the elastic rubber of the elastic roller is resistance-controlled in the medium resistance area to keep the electric field while preventing conduction with the surface of the electrostatic latent image carrier, or to provide a thin insulating layer on the surface layer of the conductive roller. Methods are also available. Further, a conductive layer is formed on the conductive roller on a conductive resin sleeve having a surface facing the surface of the electrostatic latent image carrier covered with an insulating material or on a side not facing the electrostatic latent image carrier with an insulating sleeve. The configuration provided is also possible. It is also possible to use a configuration in which a rigid roller is used as the toner carrier and the electrostatic latent image carrier is a flexible member such as a belt. The resistance of the developing roller as a toner carrying member is preferably in the range of 10 ² ~10 ⁹ Ω · cm.

When the surface shape of the toner carrier is set so that the surface roughness Ra (μm) is 0.2 to 3.0, both high image quality and high durability can be achieved. The surface roughness Ra correlates with the developer carrying ability and the developer charging ability.
When the surface roughness Ra of the toner carrier exceeds 3.0, it becomes difficult not only to reduce the thickness of the developer layer on the toner carrier but also to improve the image quality because the chargeability of the developer is not improved. I can't hope. By setting the ratio to 3.0 or less, the ability to transport the developer on the surface of the toner carrier is suppressed, the developer layer on the toner carrier is made thinner, and the number of times of contact between the toner carrier and the developer is increased. Therefore, the chargeability of the developer is also improved, so that the image quality is synergistically improved. On the other hand, when the surface roughness Ra is 0.2
If it is smaller than this, it becomes difficult to control the amount of developer coating.

In the present invention, the surface roughness Ra of the toner carrier is determined by using a surface roughness measuring device (Surfcoder SE-30H, manufactured by Kosaka Laboratory Co., Ltd.) based on JIS surface roughness "JIS B 0601". Corresponds to the center line average roughness measured. Specifically, a 2.5 mm portion is extracted from the roughness curve in the direction of the center line as the measurement length a,
The center line of the extracted portion is the X axis, and the direction of the vertical magnification is Y
When an axis and a roughness curve are represented by y = f (x), a value obtained by the following equation is represented by a micrometer (μm).

[0175]

(Equation 5)

In the image forming method of the present invention, the toner carrier may rotate in the same direction as the circumferential speed of the electrostatic latent image carrier, or may rotate in the opposite direction. When the rotation is in the same direction, it is preferable to set the peripheral speed of the toner carrier to be 1.05 to 3.0 times the peripheral speed of the electrostatic latent image carrier.

If the peripheral speed of the toner carrier is less than 1.05 times the peripheral speed of the electrostatic latent image carrier, the stirring effect of the toner on the electrostatic latent image carrier becomes insufficient, and Image quality cannot be expected. Also, when developing an image that requires a large amount of toner over a large area, such as a solid black image,
The amount of toner supplied to the electrostatic latent image is insufficient, and the image density is reduced. The higher the peripheral speed ratio, the greater the amount of toner supplied to the development site, the more frequently the toner is attached to and detached from the latent image, and unnecessary parts are collected and added to necessary parts. Thus, an image faithful to the latent image can be obtained. From the viewpoint of development and cleaning according to the present invention, when there is toner remaining after transfer in close contact with the electrostatic latent image carrier, the surface of the electrostatic latent image carrier and the portion where the toner adheres are frictionally charged by the peripheral speed difference. Since the effect of collecting the toner by an electric field after positively charging the toner is important, the higher the peripheral speed ratio is, the more convenient it is to collect the residual toner.
However, if the peripheral speed ratio exceeds 3.0, on the other hand, in addition to the various problems caused by the excessive charging of the toner as described above (image density reduction due to excessive toner charge-up, etc.), mechanical Deterioration of the toner due to stress and sticking of the toner to the toner carrier occur and accelerate, which is not preferable.

As the electrostatic latent image carrier, a-Se, Cd
A photosensitive drum or a photosensitive belt having a photoconductive insulating material layer such as s, ZnO ₂ , OPC, and a-Si is preferably used.

The binder resin of the organic photosensitive layer in the OPC electrostatic latent image carrier is preferably selected from the viewpoints of transferability and cleaning properties.
Polycarbonate resins, polyester resins, and acrylic resins are preferred.

Next, the image forming method of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 140 denotes a developing device;
Denotes an electrostatic latent image carrier, 127 denotes a transfer target such as paper, 114
Denotes a transfer member, 126 denotes a pressure roller for fixing, 128 denotes a heating roller for fixing, and 117 denotes a primary charging member that directly contacts and charges the electrostatic latent image carrier 100.

The primary charging member 117 has a bias power source 131 so as to uniformly charge the surface of the electrostatic latent image carrier 100.
Is connected.

The developing device 140 contains the toner 142, and includes the toner carrier 104 that rotates in the direction of the arrow in contact with the electrostatic latent image carrier 100. Further, the developing roller 143 for regulating the amount of toner and applying the charge, the application roller 141 rotating in the direction of the arrow in order to attach the toner 142 to the toner carrier 104 and apply the charge to the toner by friction with the toner carrier 104. It also has. A developing bias power supply 133 is connected to the toner carrier 104. A bias power supply 132 is also connected to the application roller 141, and the voltage is set to a negative side of the developing bias when using a negatively charged toner, and to a positive side than the developing bias when using a positively charged toner. Is done.

The transfer member 114 has the electrostatic latent image carrier 100
And a transfer bias power supply 134 having a polarity opposite to the above.

Here, the length of the contact portion between the electrostatic latent image carrier 100 and the toner carrier 104 in the rotational direction, that is, the so-called development nip width is preferably 0.2 mm or more and 8.0 mm or less. If the thickness is less than 0.2 mm, a sufficient image density cannot be obtained due to an insufficient development amount, and the transfer residual toner cannot be sufficiently recovered.
If the thickness exceeds 8.0 mm, the toner supply amount becomes excessive, fog suppression is likely to be deteriorated, and the wear of the electrostatic latent image carrier is adversely affected.

As the toner carrier, a so-called elastic roller having an elastic layer on its surface is preferably used.

The hardness of the elastic layer material used is as follows.
Those having a temperature of 20 to 65 degrees (JIS A) are preferably used.

The resistance of the toner carrier is preferably in the range of about 10 ² to 10 ⁹ Ωcm in volume resistance. 1
0 ² Ωcm, for example, the electrostatic latent image carrier 10
If there is a pinhole or the like on the surface of 0, an overcurrent may flow. On the other hand, when it is higher than 10 ⁹ Ωcm, the toner is liable to be charged up due to frictional charging, and the image density is liable to be reduced.

The amount of toner coating on the toner carrier is 0.1
It is preferably from 1 mg / cm ^{2 to} 1.5 mg / cm ² .
If it is less than 0.1 mg / cm ^2, it is difficult to obtain a sufficient image density, and if it is more than 1.5 mg / cm ^2, it becomes difficult to uniformly tribocharge all the individual toner particles,
It becomes a factor of deterioration of fog control. In addition, 0.2 mg /
It is more preferably not less than cm ^{2 and not} more than 0.9 mg / cm ² .

The toner coating amount is controlled by the developing blade 143. The developing blade 143 is in contact with the toner carrier 104 via the toner layer. The contact pressure at this time is 4.9 N / m or more and 49 N / m or less (5 g / cm
Is not less than 50 g / cm) is a preferable range. 4.9
If it is smaller than N / m (5 g / cm), uniform triboelectric charging becomes difficult in addition to the control of the amount of toner coating, which causes deterioration of fog suppression and the like. On the other hand, if it is larger than 49 N / m, the toner particles are subjected to an excessive load, so that the deformation of the particles and the fusion of the toner to the developing blade or the toner carrier are likely to occur, which is not preferable.

As the toner coating amount regulating member, a metal blade, a roller, or the like may be used in addition to the elastic blade for press-applying the toner.

For the elastic regulating member, it is preferable to select a material of a triboelectric series suitable for charging the toner to a desired polarity. Silicone rubber, urethane rubber, NBR
Rubber elastic body such as, synthetic resin elastic body such as polyethylene terephthalate, and metal elastic body such as stainless steel, steel and phosphor bronze. Further, a composite thereof may be used.

When durability is required for the elastic regulating member and the toner carrier, it is preferable to apply a resin or rubber to the metal elastic body so as to contact the sleeve contact portion, or to apply a coating. .

Further, an organic or inorganic substance may be added to the elastic regulating member, may be melted and mixed, or may be dispersed. For example, metal oxides, metal powders, ceramics, carbon allotropes, whiskers, inorganic fibers, dyes, pigments,
The chargeability of the toner can be controlled by adding a surfactant or the like. In particular, when the elastic body is a molded body such as rubber or resin, silica, alumina, titania, tin oxide, zirconia, metal oxide fine powder such as zinc oxide,
It is also preferable to include carbon black, a charge control agent generally used for toners, and the like.

Further, by applying a DC electric field and / or an AC electric field to the regulating member, the uniform thin layer coating property and the uniform charging property are further improved due to the loosening action on the toner, and the sufficient image density can be obtained. Achieved and good quality images can be obtained.

The cleaning member on the electrostatic latent image carrier is
It is preferable to select an elastic material suitable for rubbing and removing residual toner on the electrostatic latent image carrier. Silicon rubber, ethylene-propylene-diene terpolymer (EPDM), urethane rubber , NBR or a synthetic resin elastic material such as polyethylene terephthalate. Further, a composite thereof may be used.

It is also preferable to provide a leveling member between the cleaning member and the transfer site on the electrostatic latent image carrier. As the leveling member, a known fur brush or elastic roller is preferable, and a fur brush in which nylon fibers are arranged perpendicular to the circumferential direction is more preferable.

In FIG. 1, the primary charging member 117 uniformly charges the electrostatic latent image carrier 100 rotating in the direction of the arrow.

The primary charging member used here is a core 117b at the center and a conductive elastic layer 117 forming the outer periphery thereof.
a is a charging roller having a basic configuration. Charging roller 1
Reference numeral 17 is abutted against the entire surface of the electrostatic latent image carrier with a pressing force, and is rotated by the rotation of the electrostatic latent image carrier 100.

A preferable process condition when the charging roller is used is that the contact pressure of the roller is 4.9 to 490 N /
m (5 to 500 g / cm), and the applied voltage is a DC voltage or a DC voltage with an AC voltage superimposed thereon, and is not particularly limited. In the present invention, an applied voltage of only a DC voltage is preferably used. In this case, the voltage value is used in a range of ± 0.2 to ± 5 KV.

Following the primary charging step, an electrostatic latent image corresponding to the information signal is formed on the electrostatic latent image carrier 100 by exposure 123 from the light emitting element 121, and the toner is The electrostatic latent image is developed into a visible image. Further, in the image forming method of the present invention,
In particular, in combination with a developing system in which a digital latent image is formed on an electrostatic latent image carrier, it is possible to faithfully develop a dot latent image without disturbing the latent image.

Next, the visible image is transferred onto the transfer member 127 by the transfer member 114, and the transfer toner 129 is transferred to the heating roller 128 and the pressure roller 126 together with the transfer member 127.
To obtain a permanent image. The heating and pressing fixing means is not limited to a heating roller having a heating roller having a built-in heating element such as a halogen heater and an elastic pressing roller pressed against the heating roller with a pressing force. A method of fixing by heating with a heater via a film is also used.

On the other hand, the electrostatic latent image carrier 100
The transfer residual toner 124 remaining on the upper surface is cleaned by a cleaning unit 120 having a cleaning blade 120a and collected in a cleaning container.

Next, a full-color image forming method will be described. For a full-color image forming method, an image forming method using an intermediate transfer member, a full-color image forming method in which a color toner is directly superimposed on a transfer material and multiple development is performed, and in particular, a color developing device is inlined A full-color image forming method in which side-by-side sequential development is performed can also be suitably used in the present invention.

As an example of the image forming method of the present invention, a full-color image forming method of a contact development system using an intermediate transfer member will be described below.

In the apparatus system shown in FIG. 2, the developing units 4-1, 4-2, 4-3, and 4-4 have a developer containing a cyan toner and a developer containing a magenta toner, respectively.
A developer having a yellow toner and a developer having a black toner are introduced, and the electrostatic latent images formed on the electrostatic latent image carrier 1 are developed by the above-described developing method or the like. It is formed on the carrier 1.

As the developing means, development can be performed using, for example, a developing means having a developing device 140 as shown in FIG. Specifically, the developer 142 supplied from the application roller 141 and having its coating amount regulated by the developing blade 103 while applying a direct current or an alternating electric field to the developer carrier 104b by a power supply is supplied to the electrostatic latent image carrier 100b. Is developed in contact with When an alternating electric field is used, various types of waveforms, such as a triangular wave, a rectangular wave, a sine wave, a waveform with a changed duty ratio, and a waveform with a periodically turned off pulse, can be used. A DC electric field with a small voltage load on the latent image carrier is preferably used, and the applied voltage is a dark potential (a potential immediately after a charging process) and a bright potential (a potential after an exposure process) on the electrostatic latent image carrier. It is set to an appropriate value between

In any case, it is more preferable to set the peripheral speed of the developer carrier to be 1.05 to 3.0 times the peripheral speed of the electrostatic latent image carrier.

The developed toner image on the electrostatic latent image carrier is, specifically, an intermediate image to which a voltage (for example, ± 0.1 to ± 5 KV) is applied in the apparatus shown in FIG. The primary transfer is performed on the transfer body 5. At this time, the transfer residual toner on the electrostatic latent image carrier that has not been transferred is cleaned by a cleaning unit 9 having a cleaning blade and in contact with the electrostatic latent image carrier.

The intermediate transfer member 5 is provided in parallel with the electrostatic latent image carrier 1 so as to be in contact with the lower surface of the electrostatic latent image carrier 1. It rotates in the counterclockwise direction of the arrow at the same peripheral speed as.

In the process in which the first color toner image formed and carried on the surface of the electrostatic latent image carrier 1 passes through a transfer nip where the electrostatic latent image carrier 1 and the intermediate transfer body 5 are in contact with each other, the intermediate transfer is performed. The intermediate transfer is sequentially performed on the outer surface of the body 5. After the transfer of the toner image onto the transfer material 6, the detachable cleaning means 10
As a result, the surface of the intermediate transfer member 5 is cleaned.

A transfer means 7 is provided in parallel with the intermediate transfer body 5 and is brought into contact with the lower surface of the intermediate transfer body 5, and the transfer means 7 is, for example, a transfer roller or a transfer belt. 5 rotates in the clockwise direction of the arrow at the same peripheral speed. The transfer unit 7 may be disposed so as to directly contact the intermediate transfer member 5, or a belt or the like may be disposed so as to contact between the intermediate transfer member 5 and the transfer unit 7.

In the case of the transfer roller, the basic configuration is a core metal 7b at the center and a conductive elastic layer 7a forming the outer periphery thereof.

The intermediate transfer member 5 includes a pipe-shaped conductive core 5b and a medium-resistance elastic layer 5 formed on the outer peripheral surface thereof.
a. The cored bar 5b may be formed by applying a conductive plating to a plastic pipe.

The medium-resistance elastic layer 5a is made of silicone rubber, Teflon rubber, chloroprene rubber, urethane rubber,
Ethylene-propylene-diene terpolymer (EPD
M) and other elastic materials such as carbon black, zinc oxide,
It is a solid or foamed layer in which an electric resistance value (volume resistivity) is adjusted to a medium resistance of 10 ⁵ to 10 ¹¹ Ω · cm by mixing and dispersing a conductivity imparting agent such as tin oxide and silicon carbide.

By setting the volume resistivity of the elastic layer of the intermediate transfer member to be smaller, the voltage applied to the transfer roller can be reduced, a good toner image can be formed on the transfer material, and the transfer material can be transferred to the intermediate transfer member. Can be prevented from winding. In particular, it is particularly preferable that the volume resistivity of the elastic layer of the intermediate transfer member is 10 times or more the volume resistivity of the elastic layer of the transfer roller.

For example, the conductive elastic layer 7b of the transfer roller 7
Is polyurethane, ethylene-propylene-diene terpolymer (EPDM) in which conductive material such as carbon is dispersed
It is made of an elastic material having a volume resistance of about 10 ⁶ to 10 ¹⁰ Ω · cm. A bias is applied to the core metal 7a from a low voltage power supply. The bias condition is ± 0.2 ~
10 kV is preferred.

As described above, a toner in which fine particles containing Mg are externally added to colored particles containing at least a binder resin and a colorant,
A toner having an atomic release rate in an appropriate range and a toner surface state in an appropriate range, and a charging step of charging at least the image carrier; and a latent image forming an electrostatic latent image on the charged image carrier. An image forming step; a developing step of developing the electrostatic latent image with the toner carried on the toner carrier to form a toner image on the image carrier; and transferring the toner image on the image carrier through an intermediate transfer body. Or a transfer step of transferring the toner image onto the transfer material without or with intervention; and an image forming method having a fixing step of fixing the toner image on the transfer material, thereby suppressing fluctuations in the charging characteristics of the toner during durability. Thus, a toner and an image forming method that can always obtain a stable image can be achieved.

In addition, it is possible to achieve a toner and an image forming method capable of forming a stable image for a long period of time by minimizing toner fusion and filming on a latent image carrier due to a free external additive.

Further, the charge stability is excellent even under a severe environment.
It is possible to achieve a toner and an image forming method with less image defects due to density fluctuation due to charge-up during durability or charge-down during standing.

These are the same as those of the present invention, in which Mg
This is because by limiting the atomic release rate to an appropriate range and further defining the surface condition of the toner, it is possible to minimize the generation of substances that contaminate the developing system from the toner.

In particular, in the case of a full-color image, the effect of minimizing the generation of substances that contaminate the developing system is very remarkable.

Therefore, the toner of the present invention is a toner excellent as a material for electrophotography, which minimizes the generation of substances contaminating the developing system and maintains the performance in durability.

[0224]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to toner production examples and examples, but this does not limit the present invention in any way.

Toner Production Example 1 710 parts by mass of ion-exchanged water and 450 parts by mass of a 0.1 mol / L Na ₃ PO ₄ aqueous solution were added to a 2-liter four-necked flask equipped with a high-speed stirrer TK-Homomixer. Then, the number of rotation was adjusted to 7000 rpm, and the mixture was heated to 60 ° C. Here, 68 parts by mass of a 1.0 mol / L-CaCl ₂ aqueous solution is gradually added, and a minute hardly water-soluble dispersant Ca is added.
_An aqueous dispersion medium containing ₃ (PO ₄ ) ₂ was prepared.

On the other hand, 80 parts by mass of styrene monomer 20 parts by mass of 2-ethylhexyl acrylate monomer 0.15 parts by mass of divinylbenzene monomer 10 parts by mass of polyester (acid value 10 mg KOH / g, peak molecular weight 8500) ) ・ Carbon black (primary particle diameter 40 nm) 10 parts by mass ・ Ester wax No. 4 (R ₁ , R ₂ : C ₁₈ H ₃₇ ) 10 parts by mass ・ Dicarboxylic acid metal compound 1 part by mass After sufficiently dispersing the above material using a ball mill, the content was isolated from the ball mill. A polymerizable monomer composition obtained by adding 3 parts by mass of 2,2′-azobis (2,4-dimethylbutyronitrile), which is a polymerization initiator, to the content is charged into the aqueous dispersion medium. 7000 rpm
granulated while maintaining m. Thereafter, the reaction was carried out at 60 ° C. for 4 hours while stirring with a paddle stirring blade, followed by polymerization at 80 ° C. for 5 hours, and further at 13.3 kPa (100 Torr) at 85 ° C.
r) The amount of residual monomers in the toner was reduced by distillation under reduced pressure to the following pressure.

After the completion of the reaction, the suspension was cooled, hydrochloric acid was added to dissolve the poorly water-soluble dispersant Ca ₃ (PO ₄ ) _2, and the mixture was filtered, washed with water, dried, and then classified to a desired particle size by air classification. Colored particles (1) were obtained.

With respect to 100 parts by mass of the colored particles (1),
0.4 mass of hydrotalcite compound A shown in Table 1
Part was stirred at low speed with a Henschel mixer and mixed well.
After that, the hydrophobic silicone treated with hexamethyldisilazane
Fine powder (BET: 200m ^Two/ G) 1.2 parts by mass
The toner of the present invention is mixed in two stages by high-speed stirring.
(1) was prepared.

The Mg release rate of this toner (1) was 0.4%, and the BET specific surface area was 1.7 m ² / g.

Further, when the toner shape of toner (1) was measured, the equivalent circle diameter was 6.6 μm and the average circularity was 0.98.
3, circularity standard deviation is 0.029, 0.6 to 3.0 μm
Was 10%.

Toner Production Example 2 Using the colored particles (1) in Toner Production Example 1, 0.3 part by mass of hydrotalcite compound B was stirred at a high speed with a Henschel mixer, thoroughly mixed, and further mixed with silicone oil. Treated hydrophobic silica fine powder (BET: 3
Other modified to use a 00m ² /G)1.2 parts by weight, in the same manner as in Toner Production Example 1 to prepare a toner (2).

Toner Production Example 3 The colored particles (1) in Toner Production Example 1 were used, and instead of hydrotalcite compound A, 0.3 part by mass of hydrotalcite compound C was treated with hexamethyldisilazane. Hydrophobic silica fine powder (BET: 200 m ² /
g), except that 2.0 parts by mass of hydrophobic silica fine powder (BET: 130 m ² / g) treated with silicone oil was used instead of the toner (3). ) Was prepared.

Toner Production Example 4 Using the colored particles (1) in Toner Production Example 1, 0.3 parts by mass of hydrotalcite compound D was treated with hexamethyldisilazane instead of hydrotalcite compound A. Hydrophobic silica fine powder (BET: 200 m ²
/ G) and titanium oxide fine powder (BET: 60 m ² /
g) A toner (4) was prepared in the same manner as in Toner Production Example 1, except that 2.0 parts by mass was used.

Toner Production Example 5 Using the colored particles (1) in Toner Production Example 1, in place of hydrotalcite compound A, 0.5 part by mass of hydrotalcite compound F not subjected to surface treatment was used. was treated with hexamethyldisilazane hydrophobic silica fine powder (BET: 200m ² / g) in varied strontium titanate fine powder (BET: other modified to use a 50m ² /g)2.0 parts by weight In the same manner as in Toner Production Example 1, Toner (5) was prepared.

Toner Production Example 6 Hydrophobic silica fine powder (BET: 200 m ² / g) treated with hexamethyldisilazane using the colored particles (1) in Toner Production Example 1 at the time of external addition in the second stage Toner (6) was prepared in the same manner as in Toner Production Example 1, except that 0.5 parts by mass and 0.5 parts by mass of titanium oxide fine powder (BET: 50 m ^{2 /} g) were used in combination. .

Toner Production Example 7 Hydrophobic silica fine powder (BET: 200 m ² / g) treated with hexamethyldisilazane at the time of external addition using the colored particles (1) in Toner Production Example 1 .5 parts by mass and poly (methyl methacrylate) resin fine powder (primary particle size:
0.3 μm) The toner (7) was manufactured in the same manner as in the toner production example 1 except that 0.5 parts by mass was used together.
Was prepared.

Toner Production Example 8 Using the colored particles (1) in Toner Production Example 1, hydrophobic silica fine powder (BET: 1.5 parts by mass) treated with 1.5 parts by mass of hydrotalcite compound A and hexamethyldisilazane
300 m ^{2 /} g) 2.0 parts by mass are added simultaneously, and V
A toner (8) was prepared in the same manner as in Toner Production Example 1, except that mixing was performed using a mold blender mixer.

Toner Production Example 9 100 parts by mass of magnetic material (average particle size 0.22 μm, spherical) 100 parts by mass of styrene-butyl acrylate-butyl maleate half-ester copolymer (glass transition point Tg = 63 ° C.) 2 parts by mass of iron complex of monoazo dye (negative charge control agent) 4 parts by mass of low molecular weight polyethylene (DSC endothermic peak 106.7 ° C., Mw / Mn = 1.08) The mixture was melt-kneaded with a twin-screw extruder heated to ℃, and the cooled kneaded material was coarsely pulverized with a hammer mill, and the coarsely pulverized material was finely pulverized with a mechanical pulverizer. Colored particles (9) were obtained by strict classification with a multi-division classifier.

With respect to 100 parts by mass of the colored particles (9),
Hydrotalcites Compound A Hydrophobic silica fine powder (BE) treated with 1.5 parts by mass of hexamethyldisilazane
T: 300 m ² / g) at the same time, and mixed with a Henschel mixer to prepare a toner (9) of the present invention.

Toner Production Example 10 Using the colored particles (9) in Toner Production Example 9, 0.3 part by mass of a hydrotalcite compound A was stirred at a high speed with a Henschel mixer, mixed well, and further mixed with hexamethyldisilazane. Hydrophobic silica fine powder (BE
(T: 200 m ^{2 /} g) 2.0 parts by mass was added and mixed in two stages with a Henschel mixer. Subsequently, surface treatment was performed with a hybridizer to prepare the toner (10) of the present invention.

Toner Production Example 11 The polymerizable monomer composition in Toner Production Example 1
Further, 2.0 parts by mass of the hydrotalcite compound A was added and sufficiently stirred and mixed. Thereafter, as in the case of Toner Production Example 1, the suspension is poured into an aqueous dispersion medium, granulated, polymerized, and distilled, and after the reaction is completed, the suspension is cooled and hydrochloric acid is added to add a sparingly water-soluble dispersant Ca ₃ ( After PO ₄ ) ₂ was dissolved, filtered, washed with water and dried, the particles were classified into a desired particle size by air classification to obtain colored particles (11).

The hydrotalcite compound A0.4 shown in Table 1 was added to 100 parts by mass of the colored particles (11).
After stirring at a high speed with a Henschel mixer and thoroughly mixing, 1.5 parts by mass of hydrophobic silica fine powder (BET: 200 m ^{2 /} g) treated with hexamethyldisilazane was further added, and the mixture was subjected to two steps with a Henschel mixer. To prepare toner (11) of the present invention.

Comparative Toner Production Example 1 Using the colored particles (1) in Toner Production Example 1, hydrophobic silica fine powder (B
(ET: 200 m ² / g) Only 1.7 parts by mass was added and mixed with a Henschel mixer to prepare comparative toner (1).

Comparative Toner Production Example 2 The hydrophobic silica fine powder treated with hexamethyldisilazane in Comparative Toner Production Example 1 was changed to 4.0 parts by mass of untreated silica fine powder (BET: 300 m ^{2 /} g). A comparative toner (2) was prepared in the same manner as in Toner Production Example 1, except for changing the above.

Comparative Toner Production Example 3 Using the colored particles (1) in Toner Production Example 1, hydrophobic silica fine powder (B
(ET: 200 m ^{2 /} g) 1.0 part by mass was added, and the mixture was stirred at a high speed with a Henschel mixer and thoroughly mixed. Then, 2.2 parts by mass of hydrotalcite compound A was further added and mixed in two stages with a Henschel mixer. A comparative toner (3) was prepared in the same manner as in Toner Production Example 1, except that the toner was changed as follows.

Comparative Toner Production Example 4 An aqueous dispersion medium containing 1100 parts by mass of ion-exchanged water and 5.3 parts by mass of sodium dodecylbenzenesulfonate in a two-liter four-necked flask equipped with a high-speed stirrer TK-Homomixer Was prepared.

On the other hand, styrene monomer 108 parts by mass n-butyl acrylate monomer 20 parts by mass methacrylic acid monomer 6.7 parts by mass Dodecanethiol 2 parts by mass After adding 2 parts by mass of a nonionic surfactant (manufactured by Kao Corporation, Emulgen 950), the rotation speed was increased to 7000 rpm under a nitrogen stream.
The temperature was raised to 70 ° C. while stirring. Then, 4.5 parts by mass of potassium persulfate was added, the mixture was replaced with a paddle stirring blade, and emulsion polymerization was performed at 70 ° C. for 6 hours while stirring. When the particle size distribution of the polymer particle dispersion was measured, the volume average particle size was 1.0 μm.
Met.

Thereafter, the mixture was further adjusted to pH 7.0 with ammonia, heated to 90 ° C. and stirred for 2 hours to obtain an aggregate. The aggregate liquid mixture was washed with water and dried, and then classified by air classification to a desired particle size to obtain porous comparative colored particles (1).

A comparative toner (4) was prepared in the same manner as in Toner Production Example 1, except that the obtained comparative colored particles (1) were used. The measured BET specific surface area of the obtained comparative toner (4) was 32 m ² / g.

Comparative Toner Production Example 5 The conditions for finely pulverizing with a mechanical pulverizer in Toner Production Example 9 were changed, and the resulting finely pulverized product was strictly classified by a multi-part classifier using the Coanda effect. Thus, comparative colored particles (5) were obtained.

The comparative colored particles (5) were externally added in the same manner as in Toner Production Example 1 to prepare Comparative Toner (5).

Toner Production Example 12 In toner production example 1, C.I. I. Pigment Blue 15:38 parts by mass except that toner was used in the same manner as in Toner Production Example 1 except that 18 parts by mass was used.

Toner Production Example 13 In toner production example 1, C.I. I. A toner (13) was prepared in the same manner as in Toner Production Example 1, except that 8 parts by mass of Pigment Red was used.

Toner Production Example 14 In toner production example 1, C.I. I. Pigment Yellow 178 was used in the same manner as in Toner Production Example (1) except that 178 parts by mass of Pigment Yellow was used to prepare toner (14).

The measurement results of the Mg release rate, the BET specific surface area, the number average particle diameter of the toner, the amount of fine powder, and the average circularity of the toners of Toner Production Examples 1 to 14 and Comparative Toner Production Examples 1 to 9 are shown below. Put together in 2.

[0256]

[Table 2]

[Examples 1 to 11 and Comparative Examples 1 to 5] The image forming apparatus used in this example will be described below.

FIG. 3 is a schematic view of a modified machine of a 600 dpi laser beam printer (manufactured by Canon: LBP-860) utilizing an electrophotographic process of a non-magnetic one-component contact developing system. In this embodiment, an apparatus modified from the following parts (a) to (h) was used.

(A) The process speed was changed to 65 mm / s.

(B) The charging method of the device is direct charging performed by abutting a rubber roller, and the applied voltage is changed to a DC component (−1).
200 V).

(C) A toner bearing member is a medium resistance rubber roller (16φ, hardness ASKER C 45 degrees, resistance 10 ⁵ Ω ·) made of silicone rubber in which carbon black is dispersed.
cm) and contacted the electrostatic latent image carrier.

(D) The rotational speed of the toner carrier is the same in the contact portion with the electrostatic latent image carrier, and is 140% of the rotational speed of the electrostatic latent image carrier. Driven.

(E) The electrostatic latent image carrier was changed to the following.

As the electrostatic latent image carrier used here, 3
A 0φ, 254 mm Al cylinder was used as a substrate, and layers having the following structures were successively laminated by dip coating to form an electrostatic latent image carrier. Conductive coating layer: Mainly composed of tin oxide and titanium oxide powder dispersed in phenol resin. The thickness is 15 μm. Undercoat layer: mainly composed of modified nylon and copolymerized nylon. The film thickness is 0.6 μm. Charge generation layer: Mainly a layer in which a titanyl phthalocyanine pigment having absorption in a long wavelength region is dispersed in a butyral resin. The film thickness is 0.6 μm. Charge transport layer: Mainly a material in which a hole transporting triphenylamine compound is dissolved in a polycarbonate resin (molecular weight 20,000 according to Ostwald viscosity method) at a mass ratio of 8:10. Film thickness 20 μm.

(F) As means for applying toner to the toner carrier, an application roller made of urethane foam rubber was provided in the developing device, and was brought into contact with the toner carrier. A voltage of about -550 V is applied to the application roller.

(G) A stainless steel blade coated with a resin for controlling the coat layer of the toner on the toner carrier was applied with a linear pressure of about 19.6 N / m with the toner carrier.
(20 g / cm).

(H) The applied voltage during development is changed to a DC component (−4
50 V) only.

The electrophotographic apparatus was remodeled and the process conditions were set as follows so as to conform to the remodeling of these process cartridges.

The modified device uniformly charges the image carrier using a roller charger (only DC is applied). After charging, an electrostatic latent image is formed by exposing an image portion with a laser beam, a visible image is formed with toner, and then the toner image is transferred to a transfer material by a roller to which a voltage of +700 V is applied. An outline is shown in FIG.

The electrostatic potential of the electrostatic latent image carrier was set to -580 V for the dark portion potential and -150 V for the bright portion potential.

With the image forming apparatus, Production Examples 1 to 11,
And using the toners of Comparative Production Examples 1 to 5 at a temperature of 23 ° C. /
The durability test was performed under the condition of a humidity of 55%.

The durability test was carried out using a CLC paper manufactured by Canon Inc. with a striped image set to have a print area ratio of 3%. The above image evaluation results are summarized in Table 3 (evaluation criteria will be described later).

[0273]

[Table 3]

The image fog was poor in Comparative Examples 1 and 2. This is because the charging characteristics of the toner were not stable because the compound containing Mg was not added to the toner. it is conceivable that. Further, in Comparative Example 3, the charging roller was contaminated. This is because the release rate of the Mg-containing compound in the toner was large, and the charging of the electrostatic latent image carrier was performed by the free Mg-containing compound. This is considered to be due to contamination of the member, inhibition of charging of the electrostatic latent image carrier, and occurrence of image defects.
Furthermore, in Comparative Example 4, the result of poor fusion to the latent image carrier was poor. However, this was because the adhesion state of the compound containing Mg was out of the range of the present invention. Is insufficiently adhered to the latent image carrier in the step of contacting and developing the electrostatic latent image.
This is considered to be caused by the migration and fusion of the compound containing g. In Comparative Examples 3 and 4, the development streak was poor. This is because the Mg-containing compound adhered and deposited on the toner regulating member to form a fused mass on the toner regulating member. It is considered that the lumps make the toner layer on the developer carrier non-uniform, resulting in streak-like image defects. Further, it has been clarified that the streak-like image defects do not disappear due to durability and image defects continue to occur.

Example 12 Using the image forming apparatus used in Example 1 and the toner (1), a temperature of 30 ° C. and a humidity of 80 were used.
%, A durability test similar to that of Example 1 was performed. As a result, image fog after 5,000 sheets of durability, fusion to the latent image carrier, and contamination of the charging roller were all good.

Example 13 Under the following experimental conditions,
A durability evaluation was performed on a full-color image.

FIG. 2 is a schematic sectional view of an image forming apparatus applied to the thirteenth embodiment, and FIG. 3 is a view of a developing device of the image forming apparatus.

The electrostatic latent image carrier 1 has a photosensitive layer 1b having an organic optical semiconductor on a substrate 1a, and rotates in the direction of the arrow.
The charging roller 2 (the conductive elastic layer 2a,
The electrostatic latent image carrier 1 is charged to a surface potential of about -600 V by the metal core 2b). In the exposure, an electrostatic charge image having an exposure portion potential of -100 V and a dark portion potential of -600 V is formed by turning on and off the electrostatic latent image carrier by a polygon mirror in accordance with digital image information. Developing device 4-
1, 4-2, 4-3, and 4-4, toner is introduced respectively, and the electrostatic latent image formed on the electrostatic latent image carrier 1 by the non-magnetic one-component system is reversely developed to form a toner image of each color. Is formed on the electrostatic latent image carrier 1. The toner images are sequentially transferred onto the intermediate transfer body 5 after the development for each color, and finally are collectively transferred onto the transfer body 6. At this time, the toner remaining on the electrostatic latent image carrier 1 without being transferred is collected by the sleeve in contact with the electrostatic latent image carrier 1 at the same time as the development at the time of development, and is collected in the developing device. You.

The intermediate transfer member 5 is obtained by coating a pipe-shaped core metal 5b with an elastic layer 5a in which a carbon black conducting member is sufficiently dispersed in nitrile-butadiene rubber (NBR). The hardness of 5a is 20 degrees according to "JIS K-6301", and the volume resistivity is 10 ⁹ Ω · cm. Electrostatic latent image carrier 1
In this experiment, +700 V was applied from the power supply to the core 5b in this experiment.

The transfer roller 7 has an outer diameter of 20 mm. The transfer roller 7 is formed by forming a carbon conductive member on a core bar 7 b having a diameter of 10 mm by foaming an ethylene-propylene-diene-based terpolymer (EPDM). It has an elastic layer 7a formed by coating a substance sufficiently dispersed in a body, and the volume resistivity of the elastic layer 7a is 10 ⁶ Ω · cm.
A standard hardness according to “JIS K-6301” having a value of 35 degrees was used. Voltage is applied to the transfer roller and 11
A transfer current of μA was applied.

As the heat fixing device H, a heat roll type fixing device having no oil application function was used.

Under the above set conditions, an image having a print area of 4% was formed using the toner (1), the toner (12), the toner (13) and the toner (14) under the conditions of a temperature of 25 ° C. and a humidity of 55%. At a paper passing speed of 4 sheets / min (A4 size), an endurance test was performed on 3000 printed sheets by continuous printing to evaluate.

As a result, an image having excellent image density and transferability and having extremely little fog was stably obtained. In addition, no streaking occurred during development, and no fusion of toner was confirmed on the drum surface or the intermediate transfer member. Further, there was almost no contamination of the charging roller which rotates in contact, and no image defect due to charge inhibition was observed in the image after the durability test.

The evaluation items and evaluation criteria described in the examples of the present invention and the comparative examples will be described.

[Evaluation Items] <Image fog> The whiteness of the white portion of the printout image and the whiteness of the transfer paper were measured with a "Reflectometer" (manufactured by Tokyo Denshoku Co., Ltd.). The fog density (%) was calculated from the difference in whiteness of the paper, and the image fog was evaluated. A: very good (less than 0.5%) B: good (0.5% or more, less than 2.5%) C: practical (2.5% or more, less than 4.0%) D: impractical ( (4.0% or more)

<2> Fusion to Latent Image Carrier The surface of the latent image carrier was visually observed to confirm the fusion state, and the influence of contamination on the image due to contamination was evaluated. A: very good (a level where no fusion can be confirmed) B: good (a level where some fusion can be confirmed, but there is no practical problem) C: practical (possible fusion, but almost no appearance on the image) D: Practical level (impossible for practical use)

<3> Contamination of Charging Roller The contamination state of the primary charger and the effect of the contamination on the image were visually evaluated. A: very good (no contamination and no image defects at all) B: good (slight contamination can be confirmed, but there is no effect on the image) C: practical (contamination is present on the image D: Practically unusable (conspicuous contamination, image defects due to primary charging failure)

[0288]

As described above, according to the present invention,
For toner using an external additive containing Mg element,
By setting the external additive adhesion state on the surface of the toner particles in an appropriate range to be measured by the BET specific surface area, fluctuations in the charging characteristics of the toner during durability can be suppressed, and a stable image can always be obtained. And an image forming method is obtained.

Further, according to the present invention, a toner capable of forming a stable image for a long period of time by minimizing toner fusion and filming on a latent image carrier due to a free external additive, and an image forming method A method is obtained.

Further, according to the present invention, in particular, in the contact charging method, there can be obtained a toner which does not contaminate the charging member and the charging characteristics of the drum do not change with durability, and an image forming method.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a one-component image forming apparatus suitable for the present invention.

FIG. 2 is a schematic diagram of a full-color image forming apparatus using an intermediate transfer member suitable for the present invention.

FIG. 3 is a schematic explanatory view of a developing device suitable for the present invention.

[Explanation of symbols]

 1. 1. electrostatic latent image carrier Charging roller 4. Developing device 5. Intermediate transfer member 6. Transfer material 7. Transfer roller 100. Electrostatic latent image carrier 104. Developer carrier

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/06 101 G03G 15/06 101 15/08 501 15/08 501D (72) Inventor Kiyowa Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yuji Moriki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F-term (reference) 2H003 BB11 CC05 DD03 2H005 AA08 CA12 CA26 CB07 CB08 CB13 EA10 2H073 AA01 BA02 BA13 BA43 2H077 AD06 AD36 FA21

Claims (26)

[Claims] 1. A toner in which fine particles containing Mg are externally added to colored particles containing at least a binder resin and a coloring agent, wherein the free ratio of Mg atoms to carbon atoms is 0.001%. And a BET specific surface area of the toner of 0.5 m ² / g or more and 30 m ² / g or less. 2. The toner according to claim 1, wherein a release ratio of Mg atoms to carbon atoms is 0.01% or more and 2% or less, and a BET specific surface area of the toner is 0.5 m ² / g or more and 10 m ² / g or less. The toner according to claim 1, wherein 3. The toner according to claim 1, wherein the fine powder is a toner that is a hydrotalcite compound represented by the following general formula (1). Embedded image (Where 0 <[X = (x1 + x2 +... + Xk)] ≦ 0.
5, Y = (y1 + y2 +... + Yj) = 1−X, j
And k are integers of 2 or more, M2, M3,.
L2, L3... and L different from each other selected from the group consisting of n, Ca, Ba, Ni, Sr, Cu and Fe.
k is a different metal selected from the group consisting of B, Ga, Fe, Co, and In, and ^An- represents an n-valent anion, and m ≧ 0. ) 4. In the general formula (1), y1> y2
4. The relationship of + .. + yj is satisfied.
The toner according to 1. 5. In the general formula (1), x1> x2 +
4. The toner according to claim 3, wherein a relationship of + xk is satisfied. 6. In the general formula (1), y1> y2 +
The toner according to claim 3, wherein a relationship of ... + yj and x1> x2 + ... + xk is satisfied. 7. In the general formula (1), y1> 10 ×
The toner according to claim 3, wherein the relationship (y2 + ... + yj) is satisfied. 8. In the general formula (1), x1> 10
4. The toner according to claim 3, wherein a relationship of × (x2 +... + Xk) is satisfied. 9. In the general formula (1), y1> 10
× (y2 + ... + yj) and x1> 10 × (x2 + ... + x
4. The toner according to claim 3, wherein the relationship of k) is satisfied. 10. In the general formula (1), 0.9 ≦ x
9. The toner according to claim 3, wherein a relationship of 1 + y1 <1.0 is satisfied. 11. The toner according to claim 3, wherein the hydrotalcite compound has been subjected to a hydrophobic treatment with a surface treating agent. 12. The toner according to claim 1, further comprising an inorganic fine powder selected from silica, alumina, titania, and a composite oxide thereof. 13. The toner according to claim 12, wherein the inorganic fine powder has been subjected to a hydrophobic treatment. 14. The toner according to claim 12, wherein the inorganic fine powder has been subjected to hydrophobic treatment with silicone oil. 15. The toner according to claim 14, wherein the inorganic fine powder is treated with a silicone oil after being treated with a silane coupling agent. 16. The toner according to claim 1, which is negatively chargeable. 17. The method according to claim 1, further comprising a compound selected from the group consisting of strontium titanate, calcium titanate and cerium oxide.
6. The toner according to any one of the above items 6. 18. In a scattergram of a circle equivalent diameter-circularity scattergram based on the number of toners measured by a flow type particle image measuring apparatus, the average circularity of the toner is 0.920-0.
The toner according to any one of claims 1 to 17, wherein the circularity standard deviation is not more than 0.040 at 995. 19. A belt for charging at least the image bearing member
And a latent image forming an electrostatic latent image on the charged image carrier.
Forming an electrostatic latent image on a toner carrier;
Developing the toner image on the image carrier
An image process; a toner image on the image carrier is transferred via an intermediate transfer member.
And / or without transfer to a transfer material; transfer
Image forming method having a fixing step of fixing a toner image on a material
In the method, the toner contains at least a binder resin and a colorant.
Toner obtained by externally adding fine powder containing Mg to colored particles
And the release ratio of Mg atoms to carbon atoms is 0.1%.
001% to 10%, and BET value ratio table of toner
Area 0.5m ^Two/ G or more and 30m^Two/ G or less
A featured image forming method. 20. The image forming method according to claim 19, wherein the inorganic fine powder is a hydrotalcite compound represented by the following general formula (1). Embedded image (Where 0 <[X = (x1 + x2 +... + Xk)] ≦ 0.
5, Y = (y1 + y2 +... + Yj) = 1−X, j
And k are integers of 2 or more, M2, M3,.
L2, L3... and L different from each other selected from the group consisting of n, Ca, Ba, Ni, Sr, Cu and Fe.
k is a different metal selected from the group consisting of B, Ga, Fe, Co, and In, and ^An- represents an n-valent anion, and m ≧ 0. ) 21. In a scattergram of a circle equivalent diameter-circularity based on the number of toners measured by a flow type particle image measuring apparatus, the average circularity of the toner is 0.920 to 0.20.
21. The toner according to claim 19, wherein the circularity standard deviation is not more than 0.040 at 995. 22. The image forming method according to claim 19, wherein said toner carrier is an elastic roller. 23. The image forming method according to claim 19, wherein the bias applied to the toner carrier in the developing step is a DC voltage. 24. In the charging step, the charging member is in contact with or close to the image carrier.
24. The image forming method according to any one of 9 to 23. 25. The image forming method according to claim 24, wherein the charging member is a roller having elasticity. 26. The image forming method according to claim 19, wherein in the charging step, a bias applied to the charging member is a DC voltage.